So, here's the gist of it. For the longest time, I've been using these brushes to sketch with. I copy-and-pasted the files into Sai's main directory on my computer, and that method's worked fine.

For a new picture I'm drawing, I decided I wanted to try out some different textures without having to open Photoshop. So, I tried installing some textures I found here using the same method as last time (copy and paste to the directory), but it doesn't work. The textures save over the pencil brushes I previously installed. Even if I wanted to manually create new pencil brushes, I can't because the textures have been overridden. The only way to get the pencil brushes back is to copy and paste them into the directory, again, but then I lose the textures I just installed.

Basically, both the pencils and the textures install just fine, but I can't have both on the program at the same time. Changing certain file names so they don't override each other doesn't help.

Anyone have any suggestions on how to get both things installed?